the.com/glossiness

means The quality of having a smooth, shiny surface that reflects light clearly, rather than scattering it dully.

from From 'glossy,' which surfaces in English in the 1500s meaning smooth and shining; the deeper root is uncertain, possibly linked to Scandinavian words for glowing or blazing (compare Icelandic 'glossi,' a flame). 'Gloss' later split into a second, unrelated life — meaning a note explaining a text — which comes instead from Greek 'glossa,' tongue or language. Two different ancestries, one coincidental spelling.